How to change the width of tab labels in java but keep the "selection" options

Question

Here's one way to change the width of the tabs by overriding calculateTabWidth(...) in the JTabbedPane's UI:

EDIT: MadProgrammer's comment is correct. I've changed the sample from BasicTabbedPaneUI to MetalTabbedPaneUI, since that's the default UI used for this sample. If you're specifiying a specific L&F for your app, then change the UI accordingly.

import java.awt.*;
import javax.swing.*;
import javax.swing.plaf.metal.*;

public class CustomTabWidthDemo implements Runnable
{
  public static void main(String[] args)
  {
    SwingUtilities.invokeLater(new CustomTabWidthDemo());
  }

  public void run()
  {
    JTabbedPane tabbedPane = new JTabbedPane();
    tabbedPane.setUI(new MetalTabbedPaneUI()
    {
      @Override
      protected int calculateTabWidth(int tabPlacement, int tabIndex,
                                      FontMetrics metrics)
      {
        int width = super.calculateTabWidth(tabPlacement, tabIndex, metrics);
        int extra = tabIndex * 50;
        return width + extra;
      }
    });

    tabbedPane.addTab("JTable", new JScrollPane(new JTable(5,5)));
    tabbedPane.addTab("JTree", new JScrollPane(new JTree()));
    tabbedPane.addTab("JSplitPane", new JSplitPane());

    JPanel p = new JPanel();
    p.add(tabbedPane);

    JFrame frame = new JFrame();
    frame.setContentPane(p);
    frame.pack();
    frame.setVisible(true);
  }
}